17. Sri & Gopi Hinduja

The Hinduja brothers racked up their sizeable wealth through property development, car manufacturing, and more recently, the sale of the old War Office in London's Whitehall for £300 million.

16. The Mulliez family

Reuters

Net worth: £16.6 billion

The Mulliez family derive their wealth from the Arnaud Group, a French international retail group and corporation based in Croix, France, founded by Gerard (pictured). The group has nearly 270,000 employees across 15 countries.

15. Giovanni Ferrero and family

REUTERS/Giorgio Perottino

Net worth: £17.6 billion

Age: 52

Giovanni Ferrero has run confectionery company Ferrero SpA, best known for its Nutella chocolate spread and its Ferrero Rocher chocolates, since the death of his brother Pietro Ferrero in 2011.

14. Stefan Persson, Lottie Tham & family

Stefan PerssonWikimedia Commons

Net worth: £17.8 billion

Age: 69 & 68

The Swedish siblings own a large chunk of the H&M fashion fortune, which their father founded. Persson is chairman and CEO, while Tham owns a 5% share of the brand.

13. Georg and Maria-Elisabeth Schaeffler and family

REUTERS/Daniel Karmann

Net worth: £18.7 billion

Age: 52 & 75

Georg Schaeffler owns 80% of industrial manufacturing company Schaeffler Group, while his mother Maria-Elisabeth owns the other 20%. The company produces rolling element bearings for automotive, aerospace, and industrial uses.

12. Alain and Gerard Wertheimer

Queen Elizabeth II is pictured in 2015 presenting the pair with a trophy after their racehorse won the Elizabeth II Stakes Race run at Ascot.Getty

Net worth: £18.9 billion

Age: 69 & 66

The brothers run the House of Chanel, the world-famous fashion brand. The business came into the family after their grandfather, Pierre Wertheimer, became an early business partner with Gabrielle Bonheur Chanel, the house's founder.

11. George Soros

Thomson Reuters

Net worth: £20.7 billion

Age: 86

George Soros is a Hungarian-born American fund manager, philanthropist, and major political donor. He is known as "The Man Who Broke the Bank of England" because of his short sale of $10 billion of British Pound Sterling during the 1992 Black Wednesday currency crisis.

7. Ingvar Kamprad and family

Swedish-born Kamprad founded global furniture company IKEA. The thrifty entrepreneur says that he buys second-hand clothes to save money and espoused the virtues of frugality, simplicity, and enthusiasm in a 1976 manifesto called "A Testament of a Furniture Dealer."

6. Karl Albrecht Jr, Beate Heister & family

The pair are the children — and heirs to the fortune — of the late Karl Albrecht, who co-founded discount supermarket chain Aldi with his brother. Albrecht, who passed away in 2014, based his supermarket chain's success on a no-frills strategy similar to Wal-Mart's in America, and there are now over 10,000 stores in 18 countries.

2. Bernard Arnault

Bernard Jean Étienne Arnault is chief executive of luxury goods firm LVMH, the umbrella company for brands including fashion house Louis Vuitton and champagne house Moët & Chandon. He is the richest man in France.